Research And Design On MAC Layer Of Uplink System For The Second-generation Digtal Television

With the development of communication technology,digital TV technology is also rapidly developing.In the society of information today,the interaction between users and TV programmers' providers becomes more and more interesting and appealing.We have proposed dedicated return channel to satisfy the need of interaction.The MAC layer of Dedicated Return Channel is mainly for access and channel share of multiple users.The uplink scheduling algorithm and random access back off algorithm play an important role in the MAC layer.This paper mainly studied these two kinds of algorithms.Uplink scheduling algorithm and random access back off algorithm in traditional cellular cell cannot be directly applied to the dedicated return channel because the services in digital TV cell are large amount,small packet size and burst like video on demand and TV voting for large area(radius of up to 100km).So we need to propose new uplink scheduling and random access back off algorithms according to the features of digital TV cell.In this paper,we do research on the scheduling and random access bakeoff algorithms in traditional cellular cell.After that,we summarize the features of the network,and figure out the number of users of the digital TV cell.Then we propose a novel random access back off algorithm of D-WSRAS(Dynamic Window Size and Random Access Slot Uplink)that decides the bakeoff window size and random access resource configuration according to the estimated number of users using Bayes' theorem.We also propose a novel scheduling algorithm that allocate resource blocks to users according to their packet size,waiting time and channel condition.At last in this paper we figure out the signaling overhead caused by the proposed MAC layer algorithm and procedure design and it's substantial so we further introduce a hash-mapping based method to compress the MAC addresses of users.We make simulation and comparison for the two MAC layer algorithms using the uplink physical layer parameters of the second generation digital television.Results show that the proposed back off and scheduling algorithm can meet the demand of the uplink system.